Hydraulic engine



Sept. 16, 1958 H. KRATZ v 2,851,999

HYDRAULIC ENGINE Filed Aug. 15, 1957 2 Sheets-Sheet 1 F/GJ - sept. 16,1958 Filed Aug. l5, 1957 H. KRATZ HYDRAULIC ENGINE 2 Sheets-Sheet 2 fICQ Qc ATTORNEY United States HYDRAULIC ENGINE Hans Kratz, Duisburg,Germany, assigner to Demag- Baggerfabrik G. m. b. H.,Dusseldorf-Benrath, Germany The present invention relates to tluidpressure engines and more particularly to engines which are driven` by atiuid. such as a hydraulic liquid under pressure.

Engines of this type at the present time have several disadvantagessuch4 as their great expense and the fact that they are composed ofnumerous parts which` cause failure in the operation of the enginerather frequently. Furthermore, such engines cannot always beI driven.at as low a speed as desired, and furthermore they. cannot always beoperated with the desired uniformity and evenness because of the factthatv with some of these engines the fluid pressure engages the entirecross section of a piston during one part of the operation andonly apiston ring during another part of the operation.

One of the` objects of the present invention is to overcome the abovedrawbacks by providing a fluid pressure engine which will operate evenlyand uniformly without providing dijerent areas to be engaged by thefluid under.- pressure at different parts of the cycle of operation'.

Another object of the present invention is to provide a fluid pressureengine which is of an extremely simple construction with a minimumnumber of parts such as trans; mission gears and the like, so that thepossibility of failures in operation is reduced.

A further object of the present invention is to provide an engine of theabove type Iwhich has anelongated configuration enabling the engine tobe located without. diiiiculty within the space enclosed by a track of avehicle such as a tractorV or other heavy vehicles which are providedwith endless tracks which must be rotated forv pro pelling-the vehicle.

With the above objects in viev/thefpresent invention includes in afluid-pressure engine a pairof coaxial piston members. and a pairofcoaxial cylinder'members which respectively slidably-receive thepiston members. The engine further includes a bar and a ring means.surrounding and slidably engaging the bar and beingjturnable: about theaxis thereof. This ring means is located be.- tween and fixedto oneofthe pair of members for maintaining this one pair of members in spacedcoaxial relation with respect to each other, and a rod means is x'ed tothe other of the pair of members for maintainingfthe other pair ofmembers in spaced coaxial relation withrespect to each other. A crankmeans is operatively connected with the other pair of members, and1 apassage means is formed in theV bar. andy ring means. and-communicateswith the interiors of the cylinders for. directing fluid under pressure`to theinteriors of the cylinders and for leading fluid away from theinteriorsof the cylinders. Thus, with this construction thereciprocation of the other pair of members with respect to the one pairof members will drive the crank means and the turningof the crank meanswill cause the two pairs of memberstogether with the ring means to turn`in an oscillatory fashion with respect to the bar. A

The novel-features which areconsidered as character-V isticfor theiinvention are set forth in particular in the appendedclairns. Theinvention itself, (however, bothers? atent rice to its construction andits method of operation, together with additional objects and advantagesthereof, will be best understood from the following description ofspecic embodiments when read in connection with the accompanyingdrawings, in which:

Fig. 1 is a plan view of an engine according to the present invention;

Fig. 2 is a longitudinal sectional view taken along line 2--2 of Fig. lin the direction of the arrows;

Fig. 3 shows the engine of the invention located within the spacesurrounded by a track of a vehicle; and

Fig. 4 shows another embodiment of an enginev according to the presentinvention.

Referring to the drawings, the engine of the invention includes asupport means, in form of a base plate 1 provided with a pair ofupstanding portions 1a and 1b shown in Figs. l and 2. The portion 1a ofthe support means iixedly carries a bar 2 which is of cylindrical crosssection, so thatl this bar 2 remains stationary with respect to thesupport means. A pair of ring means 3 surround and slidably engage thebar. 2 at the opposite sides of the portion 1a of the support means,respectively, and the pair of ring means 3 are each turnable about theaxis of the bar 2 so as to oscillate with respect thereto in a mannerdescribed below. Each of the ring means 3 is located between and xed toa pair of piston members 4a and 4b so that these piston members 4oz. and4b are maintained by the ring means 3 in spaced coaxial relation withrespect to each other. A pair of cylinder members 5a and 5b respectivelyslidably receive each pair of piston members, and it will be noted thateach pair of cylinder members is respectively provided with closed endsdirected away from each other and open ends directed toward each other.Suitable sealing glands 6 are carried by each cylinder for closing offthe interior thereof from the outer atmosphere `while maintaining eachcylinder in Huidtight slidable engagement with the piston therein.

A rod means is connected to each pairV of cylinders for maintaining thesame in spaced coaxial relation with respect to each other, and this rodmeans is shown in Fig. 2 as taking the form of a pair ofelongatedparallel. rods 7 respectively extending through bores of4outwardly. directed flanges of the cylinders and being tixed thereto bythe nuts shown in Fig. 2, the flanges engaging shoulders of the rods '7.

A crank means 10 is rotatably supported by the portion 1b of the supportmeans, and this crank meansltl is provided with a pair of oppositelydirected crank pins ti'andr 9 which are respectively connectedoperatively with the two pairs of cylinders in the manner shown in Figs;l and 2. Furthermore, a flywheel 11 is connected to the crank means 10for rotation therewith.

A passage means is formed in the bar 2 and the pair of ring means 3 forleading fluid under pressure to andfrom the interiors of the cylindersso that these cylindersreciprocate with respect to the pistons and drivethe crank means. The passage means is in the form of a pair oftransversebores 2b formed inthe bar 2 at each of the portions thereofwhich are respectively surrounded by the ring means 3, and each pair oftransverse bores 2b are separated from each other by a transverseportion of the bar having a predetermined thickness.

of the bar a pair of bores 3a formed in each ring means 3, and it willbe noted from Fig. 2 that each bore 3a has.

Furthermore, the. passage means includes at diametricallyopposed-portions asesor-:v9

formed with a pair of axially extending bores 2a communicating with thetransverse bores 2b, and the pair of axial bores 2a respectivelycommunicate with a pair of conduits l?. (Fig. l), one of these conduitsl2. leading duid under pressure to the bar and the other of the conduitscarrying fluid away from the bar.

In the position of the parts shown in Fig. 2 both of the bores 3a areclosed off from and do not communicate with the bores 2b so that at theparticular moment of the operation illustrated in Fig. 2 the liuidcannot flow to or from the interiors of the cylinders shown in Fig. 2.However, as soon as the crank means starts to turn one of the cylindersshown in Fig. 2 will communicate with the fluid under pressure while thefluid in the other cylinder `will discharge therefrom.

In order that the engine will at all times start by itself as soon asfluid under pressure is delivered thereto the crank pins 8 and 9 areangularly displaced by 90 with respect to each other so that in this wayalthough the engine may start with one of the pairs of pistons in theangular position shown in Fig. 2 the other pair of pistons will be in adifferent angular position prepared to direct iiuid under pressure toone of the cylinders so that the engine will always start.

Fig. 3 diagrammatically illustrates a vehicle 2t) pro vided with a track2l which must be moved in order to propel the vehicle, and the engine 22is diagrammatically illustrated in the space surrounded by the track 21,this engine 22 being the above-described engine of the presentinvention. Because of its elongated construction the engine of thepresent invention can easily tit into the relatively long narrow spacesurrounded by a track such as the track 21 so that the structure of thepresent invention is particularly suited for propelling such track.

It will be noted that with the structure of the invention the liuidunder pressure engages the same cross sectional area of the pistons atall times so that the operation of the engine is even and uniform, andfurthermore the structure of the invention is quite simple so that thepossibility of failures in operation is greatly reduced.

Of course, the conduits 12 communicate with a suitable pump driven fromany desired source of power and with a reservoir for the liquid, theliquid being delivered from the reservoir by the pump to one of theconduits 12 and being returned by the other conduit l2 back to thereservoir.

It is not essential that the pistons be connected with the ring 3 whilethe cylinders are connected with the crank 1t), and Fig. 4 shows anengine according to the present invention where the piston and cylinderarrangement of Figs. 1 and 2 is reversed. Thus, as may be seen from Fig.4 the cylinders 5a and 5b are fixed with the ring 3 as by being formedintegrally therewith, and the pistons 4a and 4b are respectivelyslidable in these cylinders and are axially immovable with respect toeach other as the result of their interconnection by the rods 7, thesealing glands 6 providing duid-tight cooperation between the cylindersand the pistons in the manner shown in Fig. 4. rlhe crank pin 9 isconnected with the pistons. Of course, the structure shown in Fig. 4 isduplicated on the other side of the flywheel 11 in` the same way as withthe embodiment of Figs. l and 2 and the assemblies on the opposite sidesof the flywheel are angularly displaced with respect to each other by90, as was described above in connection with Figs. l and 2. It isapparent that the embodiment of Fig. 4 will operate in the same way asthe embodiment'of Figs. l and 2 and will produce the same results, theonly diiference being that in the embodiment of Figs. l and 2 thecylinders reciprocate on the pistons while in the embodiment of Fig. 4th pistons reciprocate in the cylinders.

It will be understood that each of the elements described above, or twoor more together, may also nd a useful application in other types ofengines differing from the types described above.

While the invention has been illustrated and described as embodied influid pressure engines, it is not intended to be limited to the detailsshown, since various ineditications and structural changes may be madewithout departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

l. In a fluid pressure engine, in combination, a pair of coaxialcylinder members and a pair of coaxial piston members respectivelyslidable within said cylinder members; a bar; ring means surrounding andslidably engaging said bar and being turnable about the axis thereof,said ring means being located between and fixed to one of said pair ofmembers for holding said one pair of members in spaced coaxial relationwith respect to each other; rod means extending between and fixed to theother of said pair of members for holding said other pair of members inspaced coaxial'relation with respect to each other; and passage meansformed in said bar and ring means and communicating with the interior ofsaid cylinders for directing pressure fluid to and from the interior ofsaid cylinders.

2. In a fluid pressure engine, in combination, a pair of coaxialcylinder members and a pair of coaxial piston members respectivelyslidable within said cylinder members; a bar; ring means surrounding andslidably engaging said bar and being turnable about the axis thereof,said ring means being located between and fixed to one of said pair ofmembers for holding said one pair of members in spaced coaxial relationwith respect to each other; rod means extending between and fixed to theother of said pair of members for holding said other pair of members inspaced coaxial relation with respect to each other; passage means formedin said bar and ring means and communicating with the interior of saidcylinders for directing pressure fluid to and from the interior of saidcylinders; :and crank means operatively connected with said other pairof members to be driven by the reciprocation of said other pair ofmembers with respect to said one pair of members.

3. In a fluid pressure engine, in combination, a pair of coaxial pistonsand a pair of coaxial cylinders respectively slidably receiving saidpistons; a bar formed with a pair of transverse bores passingtherethrough and separating from each other by an elongated transverseportion of said bar of predetermined thickness; ring means surroundingand slidably engaging said bar at the portion thereof formed with saidtransverse bores and being turnable :about the axis of said bar, saidring means being located 'between and lixed to one of said pair ofmembers for maintaining the same in spaced coaxial relation with respectto each other and said ring means -being formed -at diametricallyopposed parts of said bar with a pair of bores each of which has adiameter not greater than the thickness of the transverse portion ofsaid bar located between said bores thereof and said bores of said ringmeans alternatively communicating with said `bores of said bar duringoscillatory turning of said ring means with respect to said bar, saidone pair of members being formed with hollow interiors, respectively,which respectively communicate with said bores 0f said ring means; rodmeans connected to the other pair of members for maintaining said otherpair of members in spaced coaxial relation with respect to each other; apressure conduit and a discharge conduit respectively communicating withsaid transverse bores of said bar for respectively leading fluidpressure to and discharging iluid from said bores of said bar; and crankmeans operatively connected to said other pair of members to be drivenby reciprocation thereof with respect to said one pair of members.

4. In a uid pressure engine, in combination, -a bar; ring meanssurrounding and slidably engaging said bar and being turnable withrespect thereto; a pair of coaxial pistons xed to and extending fromdiametric-ally opposed portions of said ring means; a pair of coaxialcylinders into which said pistons respectively slidably extend, saidcylinders respectively having closed ends di-v rected away from eachother and open ends directed to- Ward each other; rod means iixed tosaid cylinders for maintaining the same coaxially spaced from eachother; crank means operatively connected to said pair of cylinders to beoperated by reciprocation of said cylinders with respect to saidpistons; and passage means formed in said bar and ring means andcommunicating with the interiors of said cylinders for leading fluidunder pressure to and from said cylinders.

5. In a fluid pressure engine, in combination, a bar; ring meanssurrounding and slidably engaging said bar and being turnable withrespect thereto; a pair of coaxial pistons iixed to and extending fromdiametrically opposed portions of said ring means; a pair of coaxialcylinders into which said pistons respectively slidably extend, saidcylinders respectively having vclosed ends directed away from each otherand open ends directed toward each other; rod means tixed to saidvcylinders for maintaining the same coaxially spaced from each other;crank means operatively connected to said pair of cylinders to beoperated by reciprocation of said cylinders with respect to saidpistons; and passage means formed in said bar and ring means andcommunicating with the interiors of said cylinders for leading tluidunder pressure to and from said cylinders, said passage means being inthe form of a portion of said bar formed with a pair of spacedtransverse bores separated from each other by a transverse portion ofsaid `bar of predetermined thickness and a pair of additional boresformed at diametrically opposed parts of said bar in said ring means,the additional bores in said ring means having a diameter no greaterthan the thickness of the transverse portion of said bar located betweenthe bores of said bar, and said pistons respectively being formed withaxial bores respectively communicating with said bores of said ringmeans and with the interiors of said cylinders, whereby when a uidpressure line communicates with one of the bores of said bar and a fluiddischarge line communicates with the other bore of said bar said boresof said ring means will alternatively communicate with said bores ofsaid bar to alternately lead uid under pressure to said cylinders inorder to reciprocate the same with respect to said pistons.

6. In a fluid pressure engine, in combination, support means; a barlixedly carried by said support means; a pair of ring means respectivelyslidably surrounding said bar and being turnable about the ax-s thereof;a pair of pistons respectively xed to diametrically opposed parts ofeach of said ring means and extending coaxially therefrom; a pair ofcylinders respectively slidably receiving each pair of pistons; rodmeans interconnecting each pair of cylinders for maintaining each pairof cylinders in spaced coaxial relation with respect to each other;crank means rotatably carried by said support means and connectedoperatively with both of said pairs or cylinders; and passage meansformed in said bar and said pair of ring means and respectivelycommunicating with the interiors of all of said cylinders for leadinguid under pressure to and from said cylinders so that said cylindersreciprocate in order to drive said crank means.

7. In a lluid pressure engine, in combination, support means; a barlixedly carried by said support means; a pair of ring means respectivelyslidably surrounding said bar and being turnable about the axis thereof;a pair of pistons respectively xed to diametrically opposed parts ofeach of said ring means and extending coaxially therelfrom; a pair ofcylinders respectively slidably receiving each pair of pistons; rodmeans interconnecting e-ach pair of cylinders for maintaining each pairof cylinders in spaced coaxial relation with respect to each other;crank means rotatably carried by said support means and connectedoperatively with both of said pairs of cylinders; the portions of saidpairs of cylinders which are connected to said crank means beingangularly displaced with respect to each other by about the turning axisof Said crank means; and passage means formed in said bar and said pairof ring means and respectively communicating with the interiors of allof said cylinders for leading fluid under pressure to and from saidcylinders so that said cylinders reciprocate in order to drive saidcrank means.

8. In a fluid pressure engine, in combination, support means; a bartixedly carried by said support means; a pair of ring means respectivelyslidably surrounding said bar and being turnable about the `axisthereof; a pair of pistons respectively fixed to diametrically opposedparts of each of said ring means and extending coaxially therefrom; apair of cylinders respectively slidably receiving each pair of pistons;rod means interconnecting each pair of cylinders for maintaining eachpair of cylinders in spaced coaxial relation with respect to each other;crank means rotatably carried by said support means and connectedoperatively with both of said pairs of cylinders; passage means stormedin said bar and said pair of ring means and respectively communicatingwith the interiors of all of said cylinders for leading fluid underpressure to and from said cylinders so that said cylinders reciprocatein order to drive said crank means; and ywheel means connected to saidcrank means -for rotation therewith.

References Cited in the le of this patent UNITED STATES PATENTS 373,880Case Nov. 29, 1887 373 922 Case Nov. 29, 1887 479,012 Moss July 19, 1892

